What is interesting about those heads is their counterbalance mechanism. Unlike lower-end heads, these heads have a nitrogen gas piston for counterbalance. We looked at the Nitrotech N8 and it supports quite a load (up to 8kg). The head provides continuous counterbalance power. This means that when you let go of the handle, the head keeps its position as if it was locked in place.
There are two models in the Nitrotech family: